Small problem

luckyboy

I have a new ADSL line
my problem is that line may open www.hotmail.com so fast and don't open www.mail.yahoo.com at all.
why .... ?
I still three days can't access my yahoo account.

I think it is due to Firewall or other configurations on the router.
Is that right ?

Please recommend me a way to solve this problem
( Don't say contact your Network Admin )
because i think he doesn't understand what "Networking" means.